Svchost.exe is a windows operating system file and you will see a lot of activity with this during normal functioning of the window operating system. Because of how common it is though, a lot of malware will use that name, or similar names like scvhost, vcshost, etc. If you have multiple svchost.exe files on your system best bet is to make sure you have an updated antivirus software scanning your system at all times. The legitimate copy of svchost.exe will be running from the c:\windows\system32 directory, but you may also find copies in C:\Windows\ServicePackFiles\i386 and C:\Windows\$NtServicePackUninstall$ which are also legitimate places for this file to be found, but it should never be running from those locations, it should only be running from the c:\windows\system32 directory.
msfeedssync.exe is also a windows file that allows for synchronization of different "information feeds" that have been signed up for, such as RSS feeds. What feeds and from what websites you signed up to receive those feeds from will determine will determine how quickly the data is updated. What you blocked was the file going out to try and synchronize the feeds that the system is subscribed to. In order to receive those feeds you will need to allow msfeedssync.exe to access the internet again and allowing it will depend on what you actually blocked it with.
Thank you, most belatedly for your answer which makes great sense. Unfortunately before I could read it I had managed to confuse my computer totally ... so have been getting it going again and catching up with the work.
My apologies for acknowledging your reply so late.